The present invention relates generally to lift systems for implements, and more specifically, to a lift system having a pair of lift arms connected between a vehicle and an implement with a lift cylinder connected to the arms.
Various types of machines, such as a front mounted mower, utilize a pair of lift arms pivotally connected to a vehicle and extending forwardly therefrom to pivotal connections with an implement such as a mower deck. Various combinations of cylinder and lift linkages have been available to raise and lower the lift arms and to permit the implement to follow ground contours. One type of system available on the John Deere Model F910 front mounted mower includes a pair of cylinders, one cylinder connected to each lift arm with the cylinders being connected in parallel. The two cylinders not only increase the cost and complexity of the hydraulic system, but any unequal distribution in weight on the lift arms results in one of the arms raising before the other one when the implement is lifted toward the transport position. The arm carrying the most weight will also be the first to lower to the working position.
Although various systems have been devised which utilize a single lift cylinder, most of these systems suffer from one or more disadvantages. Some systems utilizing a single cylinder fix the lift arms for movement together or otherwise severely limit the independent vertical action of the arms thereby limiting the ground contour following ability of the implement. Other systems utilize a single cylinder and a lift arm arrangement connected to a pair of chains which are in turn connected to the lift arms. Mechanical linkages such as chains or the like are also relatively bulky and unsightly. In short, most single cylinder lift arrangements have not been able to effectively provide a combination of level lift, good contour following ability, and a good flotation function in a compact and sightly package.